This invention relates to apparatus for the suppressing of dust during the discharge of bulk or granular materials, such as grain, fertilizers, coal, powdered chemicals, crushed rock, sand, ore, and the like, especially in association with loading of such materials into transport vehicles such as rail cars, trucks, barges, ships and the like. It is of particular utility in association with the loading of phosphate rock, and the like.
Granular or particulate materials are commonly sold and transported in bulk. Typically such materials may be loaded into transport vehicles, such as railroad cars, ships and the like by transport from a reservoir or storage area through a conveyor system to a point above the transport vehicle employed and then allowed to fall through discharge chutes or spouts into a container or hold of the transport vehicle. Some bulk materials such as grain, tend to discharge a great deal of the entrained dust into the air as the material is falling downwardly. In addition, dust is generally released into the air when the falling stream of particles impacts with the bulk material pile in the vehicle. One common approach to controlling the emission of dust into the atmosphere is to enclose the falling column of granular material within a flexible conduit and, using an aspirator means, create a countercurrent of air to carry the dust to a disposal means such as a filter. In the case of lower density bulk materials, such as grain and the like, a major portion of the dust may be discharged from the falling stream of material and thus may be, to a great extent, controlled by such aspirator means. However, in the case of denser bulk materials, such as dry phosphate rock, a major portion of the dust is discharged when the falling material impacts with the pile being deposited in the vehicle. The control of dust by vacuum or aspirator means at this point is generally less efficient. It is to the control of dust created at this point that the present invention is primarily directed.
It will be appreciated that the discharge of dust during such loading operations is disadvantageous for a number of reasons. First, the loss of material as a result of the dispersal of dust may represent an economic loss. More importantly, the discharge of dust into the atmosphere creates an environmental hazard in the pollution of the surrounding air. The polluted air may be deleterious to workers as well as others in the area who are breathing the air. Workers may be protected by means of suitable respiratory masks or other protective breathing apparatus. Such solution, however, is not only inconvenient and expensive, but in addition is limited to workers in the immediate area, and does not afford protection to others who may be near enough to be affected by the polluted air. In addition, the discharge of dust into the atmosphere decreases visibility and may present a safety hazard from the decreased visibility as well as a health hazard from the air pollution.
Increasing recognition of such health and safety hazards has resulted in the enactment of legislation dealing with the protection of air quality and requiring control of the discharge of dust and particulate matter into the atmosphere.
Accordingly, it is a primary object of the invention to provide apparatus which will suppress or inhibit the release of dust during the discharge of granular or bulk material. It is a further object to provide apparatus which is particularly useful in the suppression of dust emission during the loading of dense granular or bulk material, such as dry phosphate rock into the container or hold of a transport vehicle, such as a railroad car, truck, ship or barge.